How to optimize this scene's render time in cycles
There are 2 things that I know of that you could do. One, if your looking for low quality but faster speeds, you could bring the samples down, but I am sure you already know about that. Another thing, from the picture it doesn't look like you have any glossy shaders. If you don't have any, go to the part where it says bounces on the render panel, go to the part where under bounces and turn glossy to 0. This will make it so it doesn't calculate the reflections for the glossy shaders.